Abstract: A MICrowave RADiometric (MICRAD) guidance system is disclosed which utilizes an antenna having four beams, designated right, left, up and down. Information from the four beams is monitored essentially 100% of the time by passing through appropriate ferrite cross-switching means to four separate receivers. Information from two of the receivers passes through a first multiplexer and feedback gain balancer to provide a target azimuth output, and information from the remaining two receivers passes through a second multiplexer and feedback gain balancer to provide a target elevation output. A local oscillator heterodynes each of the four receivers in common, and a switch driver couples each of the multiplexers to the ferrite cross-switching means and gain balancers for appropriate selection.

Abstract: A radiometer circuit for determining the character of the modulation of a signal received from a radio frequency transmitter. The circuit will determine if the transmission is one of the following classes: continuous wave (CW) frequency modulated CW (FMCW), noise modulated FMCW and noise; or pulse modulated, burt pulse modulated, random pulse modulated, or any pulse modulated noise. A single radio frequency amplifier is used to detect and discriminate between pulsed and CW transmissions.

Abstract: An apparatus and method removes interfering noise pulses from low-level ro-frequency signals through the application of a video-frequency circuit which causes detection of interfering pulses above an automatically and dynamically established threshold voltage level. Upon detection of an interfering pulse a control signal activates a hold circuit causing the conventional radiometric circuit to be interrupted during the period of the occurrence of the interfering pulse, thereby blocking passage of the pulse, while simultaneously the voltage level of the video-frequency signal is held constant.

Abstract: A radar radiometer apparatus including a superheterodyne amplifier, a synonous demodulator, and logic circuitry to provide for the interruption of a local oscillator for a portion of each pulse of a radio frequency repetition cycle in order to isolate radar receiver/transmitter coupling and permit simultaneous radiometer use.